The present invention relates to a gas turbine unit and a gas-turbine cooling method.
It is required to increase the capacity and the efficiency of gas-turbine power-generating equipment to meet the ever-increasing demand of electric power and address the problem of the warming up of the earth. In the case of gas-turbine power-generating equipment, in particular, wherein air compressed by a compressor is fed to a combustor, fuel is fed to the combustor to be burned, and the combustion gas drives a gas turbine, its capacity and efficiency can be increased by raising the combustion temperature.
However, the gas turbine exposed to and driven by combustion gas of high temperature may be damaged, if not cooled, and such damage may lead to a serious accident of the gas-turbine power-generating equipment. Therefore, in the gas-turbine power-generating equipment using the high-temperature combustion gas, the high-temperature part of the gas turbine is cooled with compressed air or steam.
Besides, the efficiency of gas-turbine power-generating equipment can be increased by collecting heat from the refrigerant after it cools the high-temperature part of the gas turbine. On the other hand, it is desirable to reduce the flow rate of the refrigerant as low as permissible.
The configuration of the cooling holes to cool the high-temperature part of the gas turbine is complex for higher cooling efficiency. Accordingly, if dust, etc. disturb the smooth flow of refrigerant or cooling holes are clogged with dust, etc., the cooling efficiency decreases and the gas turbine may be damaged. Therefore, the gas turbine requires highly purified refrigerant. Besides, refrigerant for cooling the high-temperature part of the gas turbine is required to be highly purified so that the refrigerant can flow smoothly through the complex cooling holes, its flow rate can be reduced as low as permissible, and the efficiency of the gas-turbine power-generating equipment can be increased.
For example, Japanese Unexamined Patent Application No. 54-82518 disclosed a configuration of air-cooled gas turbine wherein air discharged from a compressor is cooled by a heat exchanger, the pressure of the air is raised by a booster compressor, and the air is fed to the high-temperature part of the gas turbine to cool the part and collected to a combustor.
Japanese Unexamined Patent Applications Nos. 2-264127, 2-267326, 7-189740, and 7-317562 disclosed technique for cooling the high-temperature part of the gas turbine.
In the case of the above air-cooled gas turbine, such problems are not addressed as the generation of mist due to the cooling of air by the heat exchanger, the damage of the booster compressor due to alien substances in cooling air, the decrease of the cooling efficiency and the damage to the turbine due to the clogging of cooling holes with alien substances in cooling air, and so on.
For example, if cooling air contains alien substances such as dust, the cooling holes, of which the configuration is complex for high cooling efficiency, may get clogged with such alien substances, reducing the flow rate of the refrigerant, and the gas turbine may be damaged.
The object of the present invention is to provide a gas turbine unit and a gas-turbine cooling method capable of feeding cooling air suitable for cooling the high-temperature part of the gas turbine.
The gas turbine unit of the present invention comprises a compressor to compress and discharge gas, a combustor which the gas compressed by the compressor is fed to, and a turbine to be driven by the combustion gas of the combustor.
Further, primarily, its feature is that the gas turbine unit of the present invention has a turbine-cooling system to feed the gas from the compressor to the turbine. The turbine-cooling system comprises a heat exchanger to cool the gas compressed by the compressor and a means for separating liquid from the gas cooled by the heat exchanger.
The gas-turbine cooling method of the present invention for cooling a gas-turbine unit, which comprises a compressor to compress and discharge gas, a combustor which the gas compressed by the compressor is fed to, and a turbine to be driven by the combustion gas of the combustor, includes the process of feeding the gas from compressor to the turbine to cool it. The turbine-cooling process comprises the steps of cooling the gas compressed by the compressor and separating liquid from the cooled gas.